The present invention relates to an electrophotographic image forming apparatus, and a process cartridge removably mountable in the main assembly of an electrophotographic image forming apparatus.
Here, an electrophotographic image forming apparatus means an apparatus which forms an image on recording medium with the use of an electrophotographic image formation process. It includes, for example, an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, LED printer, and the like), a facsimile apparatus, a word processor, and the like.
A process cartridge means a cartridge in which a charging means, a developing means or a cleaning means, and an electrophotographic photosensitive member, are integrally placed, and which is removably mountable in the main assembly of an image forming apparatus. It also means a cartridge in which at least one processing means among a charging means, a developing means, and a cleaning means, and an electrophotographic photosensitive member, are integrally placed, and which is removably mountable in the main assembly of an image forming apparatus, and a cartridge in which at least a charging means and an electrophotographic photosensitive member, are integrally placed, and which is removably mountable in the main assembly of an image forming apparatus.
Conventionally, an image forming apparatus which employs an electrophotographic image formation process also employs a process cartridge system. According to a process cartridge system, an electrophotographic photosensitive member, and a single or plural processing means, which act on an electrophotographic photosensitive member, are integrally placed in a cartridge which is removably mountable in the main assembly of an image forming apparatus. Also according to this process cartridge system, an image forming apparatus can be maintained by users themselves without relying on service personnel, and therefore, operational efficiency can be drastically improved. As a result, a process cartridge system is widely used in the field of the image forming apparatus.
In order to make it easier to removably mount the aforementioned process cartridge in the main assembly of an image forming apparatus, it is customary that the image forming apparatus main assembly is provided with a pair of guide rails, which are located on each side of the apparatus main assembly, one for one, with respect to the direction in which the process cartridge is inserted, whereas the process cartridge is provided with a pair of guide ribs, which are located at the locations corresponding to the aforementioned guide rails on the apparatus main assembly side.
It has been known that a multicolor image forming apparatus, in which a plurality of process cartridges different in color of the developer they contain are removably mounted in parallel to form a multicolor image, is available. It has also been known that the provision of guide rails and guide ribs such as the those described above makes it easier to removably mount the process cartridges even in this type of a multicolor image forming apparatus.
When this type of structure is adopted, if the guide rails on the left and right sides are at the same level, it is possible that a process cartridge will be reversely inserted into the apparatus main assembly, with respect to the front and back sides in terms of the cartridge-insertion direction.
In addition, in the case of the aforementioned multicolor image forming apparatus, it is necessary to provide a wider space between the adjacent two cartridges in order to prevent the guide ribs of the adjacent two process cartridges, and the guide rails which support these guide ribs, from interfering with each other. This makes it difficult to reduce apparatus size.
The present invention is a result of the further development of the above described prior technologies.
The primary object of the present invention is to provide a process cartridge smoothly mountable in the main assembly of an electrophotographic image forming apparatus, and an electrophotographic image forming apparatus in which such a process cartridge is removably mountable.
Another object of the present invention is to provide a process cartridge mountable in the main assembly of an electrophotographic image forming apparatus without causing a directional mistake concerning the front and rear sides of the process cartridge in terms of the process cartridge insertion direction, and an electrophotographic image forming apparatus in which such a process cartridge is removably mountable.
Another object of the present invention is to provide a process cartridge configured to reduce the space necessary between two adjacent process cartridges when a plurality of process cartridges are horizontally mounted in parallel in the main assembly of an electrophotographic image forming apparatus, and an electrophotographic image forming apparatus in which such a process cartridge is removably mountable.
Another object of the present invention is to provide a process cartridge, the guide portions of which and the guide portions of adjacent process cartridges permitting vertical stacking of a plurality of process cartridges when they are horizontally mounted in parallel in the main assembly of an electro-photographic image forming apparatus, and an electrophotographic image forming apparatus in which such a process cartridge is removably mountable.
According to an aspect of the present invention, there is provided a process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, comprising a cartridge frame; an electrophotographic photosensitive member; process means actable on said photosensitive member; a first cartridge guiding portion for being guided by a main assembly guide provided in the main assembly of the apparatus when the process cartridge is mounted to the main assembly of the apparatus, the first cartridge guiding portion being provided at one end, with respect to a mounting direction in which the process cartridge is mounted to the main assembly of apparatus of the cartridge frame; and a second cartridge guiding portion for being guided by the main assembly guide provided in the main assembly of the apparatus when the process cartridge is mounted to the main assembly of apparatus, the second cartridge guiding portion being provided at the other end, with respect to the mounting direction, of the cartridge frame, wherein when the process cartridge is mounted to the main assembly of the apparatus, the first and second cartridge guiding portions are at different heights.
These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings.